ip link: missing options in bond usage

Signed-off-by: Arthur Gautier <baloo@gandi.net>

ip/iplink_bond.c

@@ -145,7 +145,7 @@ static void print_explain(FILE *f)
 		"ARP_ALL_TARGETS := any|all\n"
 		"PRIMARY_RESELECT := always|better|failure\n"
 		"FAIL_OVER_MAC := none|active|follow\n"
-		"XMIT_HASH_POLICY := layer2|layer2+3|layer3+4\n"
+		"XMIT_HASH_POLICY := layer2|layer2+3|layer3+4|encap2+3|encap3+4\n"
 		"LACP_RATE := slow|fast\n"
 		"AD_SELECT := stable|bandwidth|count\n"
 	);